1. Technical Field
The present invention relates to absorbent articles which have a tear line defined thereon and a tear line guide means. The invention is particularly well suited for single or multiple layer composite tear line guide containing absorbent articles which include at least one layer formed from a mixture of thermoplastic and other nonthermoplastic fibers, such as wood pulp fibers.
2. Description of The Prior Art
Absorbent articles formed of a combination of thermoplastic and other fibers, such as wood pulp fibers, are known. However these prior articles are not known to include tear lines with means for guiding the severing of the articles along the tear line.
For example, U.S. Pat. No. 4,458,042 of Espy discloses an absorbent material comprised of a heat consolidated blend consisting essentially of wood pulp fluff and wetting agent treated spurted polyolefin pulp. This patent does not describe any tear lines, let along any tear line guide means.
U.S. Pat. No. 4,609,580 of Rockett et al. discloses an absorbent floor mat comprising a combination of a nonwoven liquid permeable wear surface, such as a nylon web, an absorbent inner layer of a coformed mixture of polymeric microfibers and wood pulp, and a liquid impervious polymer film backing layer. Intermittent bonds, such as a line pattern, within the periphery or field of the floor mat are provided. These bonds are formed by a patterned application of sonic energy or heat and pressure. These bond lines are not described or understood to be tear lines, and no tear line guide means is disclosed.
Another example of a pad which exemplifies the prior art is described in U.S. Pat. No. 4,650,481 of O'Connor et al. The pad of O'Connor et al has a liquid impermeable backing sheet, such as polymer films, an overlaying liquid permeable face sheet, such as spun bonded polypropylene, and an absorbent coform layer between the backing and face sheets. The interior of the pad is provided with a quilted pattern of compression lines. These compression lines are described as being formed by ultrasonic bonding, by heat and compression, or by the use of glue and compression. In an illustrated example, the pad is generally rectangular and the quilting lines appear to form a pattern of squares on the pad. The backing sheet is described as being generally bonded to the absorbent material by adhesive. The quilted pattern is not described or understood to form a tear line, and no tear line guide means is described in this patent.
Tear lines have been provided in other types of nonabsorbent materials.
For example, U.S. Pat. No. 2,990,101 of Mead et. al. discloses a bag for milk and the like made from a flattened tubular strip of a suitable flexible plastic, such as polyethylene. In one form of bag (FIGS. 16 and 17), a heat sealed strip extends across the upper end of the bag and a pair of heat sealed sections extend downwardly from this upper sealed strip. A line of perforations extends along the top of the bag below the heat sealed strip and across the first and second heat sealed sections. Elongated cuts, at least one of which is shown to intersect an intermediate point of a perforation along the upper heat sealed strip, extend downwardly from the perforation line in these first and second heat sealed sections. These cuts terminate in holes. Mead et. al. indicates that these holes prevent the cuts from extending further into the bag, particularly across the adjoining portion of the heat sealed sections.
Pressure sensitive labels are shown in U.S. Pat. No. 3,706,626 of Smith et. al. and also have tear lines. In Smith et. al., a sheet of pressure sensitive labels is mounted to a backing sheet, such as of glassine paper. The labels are arranged in longitudinal and transverse rows. The labels in transverse rows are completely severed from the labels of adjacent transverse rows. The labels of longitudinal rows are only partially severed, as by perforations, from the labels of adjacent longitudinal rows. The backing sheet is perforated or partially severed only along the same transverse lines as the labels. Holes at the corners of the labels pass through both the label sheet and the backing sheet. These holes form notches at the edges of the strip of labels when a strip is torn from the label sheet. As described in this reference, it is easier to commence the tear across the longitudinal perforated lines when these notches are present. In contrast, Smith et. al. describes the prior art as comprising a pressure sensitive label sheet which is cut to a desired depth to define the labels, without slicing through the backing sheet.
U.S. Pat. No. 4,500,580 of Luciani describes a taping paper for sealing a gap through sheet rock, such as around a pipe. This taping paper may be doughnut shaped with concentric circular rows of tear lines. A radially extending row of perforations provides access to each of these circular rows from the edge of the taping paper. In the configuration shown in FIG. 2, this radially extending row of perforations intersects an intermediate portion of a perforation of the outermost circular row, intersects the end of a perforation of the next circular row, is positioned between perforations of the third circular row, and intersects an intermediate portion of a perforation of the innermost circular row.
Finally, U.S. Pat. No. 1,442,056 of Edmonds describes a paper sheet which is scored to define rectangular items such as blank checks. Perforations or holes are positioned along these score lines to facilitate removal of the checks from a sheet of checks. A hole is provided at the intersection of two tear lines, for example at a corner of the check. As described by Edmonds, this positioning of the hole contributes to the safe turning of the tear line in the required direction at the corner.
None of the above reference recognize any need for absorbent materials with tear lines and tear line guide means for guiding the selective tearing of such materials along the tear line.
Therefore, a need exists for improved absorbent materials and articles with a tear line guide means. In addition, a particular need exists for absorbent thermoplastic containing materials, such as of thermoplastic and other fibers, with a tear line guide means.